A part of the brain that helps stop humans from making bad decisions and acts as our conscience has been discovered by scientists.

The small ball of neural tissue, named the lateral frontal pole, is vital for pondering the ‘what ifs’ of life, researchers said.

Other parts of the brain keep tabs on how well decisions are working, but this new region thinks over what we might have done instead.

Scientists at Oxford University made the discovery after scanning human brains in two different ways.

Scans from 25 men and women showed that this part of the brain is made up of a dozen smaller sections. The scans were then compared with monkey brains.

The scans showed that there is nothing like it in the brain of the macaque monkey, despite it being one of our closest relatives.

Eleven of the 12 sections in the network were similar – they were found in both humans and monkeys and connected up to other, more distant, brain areas in similar ways.

But one, the lateral frontal pole prefrontal cortex, was missing in the macaques, despite it being one of our closest relatives.

Differences in the human and monkey brain have been found before, but this is special because it is the first time such a clear change has been spotted in the region behind flexible thought.

Oxford University scientist Matthew Rushworth said: ‘We’ve identified an area of the brain that appears to be uniquely human.’

The lateral frontal pole prefrontal cortex is found at the very front of the brain – with one just above each eyebrow.

In some people, it is the size of a Brussels sprout; in others, it is as big as a tangerine.

Previous research has shown it is particularly important in multi-tasking. For instance, if we decide to do one thing, it will continue to evaluate the other option – or think about what might have been.

While this might seem odd, it is good preparation for a later change of mind.

The tiny brain region helps us learn from watching others’ mistakes, speeding up the acquisition of new skills.

The study, published in the journal Neuron also revealed the people to have stronger wiring to brain regions involved in hearing – perhaps helping explain our ability to speak.

Such work could help shed light on psychiatric conditions including ADHD and obsessive compulsive disorder, as well as improve understanding of how speech is damaged by a stroke.